I run Dpup Exprimo 5.X.3.4.2.8 on a 512Mb laptop. Booting is from CD. The xxxxsave.sfs file (personal file) is on a flash disk. I do not use a swap file.

I started off with a 64Mb save file size. No problems until I started using Firefox and installed new programs. Running out of save space, I first increased it with 64Mb, then 128 Mb and lastly with 256Mb between restarts. That adds up to 512 Mb, right?. At that point, some 300Mb was still free, not used by Puppy.

However, problems arose, like slowing down and freezing. Dmesg reported problems on the flash disk and suggested to do a e2fsck.

After renaming the save file, restart of Puppy and creation of a new save file of 512Mb, all was back to normal. When I checked the file size of the old (renamed) save file, it was 562Mb in stead of 512Mb.

When I tried to unsquash the old save file, I got an error: 'Can't find a SQUASH superblock on.....'.

Now wonder I ran into troubles with the old save file....Edited_time_total

However, problems arose, like slowing down and freezing. Dmesg reported problems on the flash disk and suggested to do a e2fsck.

Who knows what this did to the old save file. Could explain size mismatch. Asking to do a e2fsck on the file system, is usually correcting file system errors, such as size reporting.

Have you tried this on a good working save file with no reported errors or other problems?
What program are you using to report file size?_________________I have found, in trying to help people, that the things they do not tell you, are usually the clue to solving the problem.
When I was a kid I wanted to be older.... This is not what I expected

If something is plugged into "other" or a dongle removed, the memcard reader reassigns the USB ports (including the card reader port), which it is supposed to do. This somehow messes up the save file on the SD card.

Here the Puppy save file is not touched when something is plugged into "other". It's "safe". There are no problems with the SD card.

Still, in this setup, USB port reassignment has some awkward effects. When something is plugged into "other", WiFi and BT are cancelled, reassigned and restarted. Or, if the BT dongle is removed, WiFi is cancelled. Same if the other way around. But that's something I can live with.

@Karl
The memcard reader incl. 3x USB port is an unknown-made-in-China-rebranded-20-in-a-dozen-run-off-the-mill thingy, so I can't provide more info. However, I bet an awful lot of USB hubs will have the same chip, whatever it is.

I attached a sketch. In situation 1 there are problems with the Puppy save file when something is plugged in/out port A or B of USB hub 1 or USB hub 2.
In situation 2 there are no such problems with Puppy save.